const readline = require("readline");
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
let num
rl.on("line", (line)=>{
    if(num === undefined) {
        num =  Number(line.trim())
        console.log(getResult(num))

        // clear
        num = undefined
    }
})

/**
 * 数字转字符, 26进制
 */
function getResult(num){
    let arr = []
    let result = ""
    //while(num > 0 ) {
    //    let res = num%26
    //    if(res === 0) {
    //        res = 26
    //    }
    //    arr.push(res)
    //    num = (num - res)/26
    //}
    while(num > 0 ) {
        let res = (num - 1)%26 // 0--25
        arr.push(res)
        num = Math.floor(num / 26)
    }

    arr.reverse()
    for (const number of arr) {
        let code = "a".charCodeAt(0)
        //code = code + number - 1

        result += String.fromCharCode(code)
    }

    return result
}